The conventional wisdom about New Jersey Gov. Chris Christie’s political fortunes is that he still has a shot at the 2016 Republican presidential nomination — if he can just get past Bridgegate, the scandal over his aides’ allegedly politically motivated partial closure of the George Washington Bridge last year.

In that regard, Christie’s fortunes have arguably improved since the memorable January news conference in which he condemned his aides but denied advance knowledge of their wrongdoing. No one has yet produced a “smoking gun” to disprove his version; polls still put him in the top tier of GOP contenders; and he’s resumed fund-raising for Republican candidates in 2014, with an itinerary that includes Iowa, New Hampshire and South Carolina.

Charles Lane

Lane is a Post editorial writer, specializing in economic policy, financial issues and trade, and a contributor to the PostPartisan blog.

Alas for Christie, his problems go deeper than Bridgegate: Specifically, he’s governor of a state that may not actually be governable.

Estimated at $46.4 billion by Pew Research, New Jersey’s unfunded pension liability is one of the worst in the nation on a per-capita basis, the product of decades of political log-rolling in which elected officials promised government employees generous benefits but declined to cut spending or raise taxes enough to pay for them.

New Jersey’s pension hole is a monument to avoidance, dishonesty and dysfunction, like the unfunded liabilities that helped bring down Detroit and that may cripple other states as varied as Illinois, Kentucky and Hawaii.

Christie came to office in 2009 vowing to end that dysfunctional business as usual, and, with bipartisan support from a Democratic legislature, he managed to enact reforms that would have put the state on a path to pension sustainability by 2018.

Pension reform was the signature accomplishment of his first term and one of the keys to his reelection. It presumably would be a cornerstone of Christie’s case for the presidency if he runs.

On May 20, however, Christie threw all that into doubt. He announced that New Jersey would have to cut a scheduled payment to the state’s pension fund by $900 million this year; he also requested legislative authority to reduce next year’s payment by $1.5 billion.

Turns out that the state badly overestimated how much revenue it would reap, so it can’t make the pension payments and still balance the budget as required by the state constitution.

To be sure, New Jersey Democrats argue that Christie could have raised the money to pay for pensions by imposing a millionaire’s tax. Christie responded, with some validity, that the tax would not have raised anywhere near enough to fund the pensions anyway — and it would have risked an exodus of the state’s already heavily taxed well-to-do residents.

Democrats and unions have a better point, however, when they complain that it’s unfair for Christie to withhold funding given that pension reforms called on them to make sacrifices, including a higher retirement age and cost-of-living adjustments. Some 14 public-sector unions are suing in state court to force Christie to make the contributions.

The main point is that Christie’s state seems to have arrived at the predicament so often forecast for states and cities that failed to strike a balance between their long-term commitments to public employees and their capacity to pay for them: a future of never-ending zero-sum budget crises in which all the choices — service cuts, tax increases, gimmicks and skipped pension contributions — are unpleasant.

Or, as Standard and Poor’s describes the state’s future in a June 2 report: “a large and growing structural budget imbalance, increased reliance on one-time measures, which are becoming less conventional with long-term implications for the state’s liability profile, and ongoing budgetary, liquidity and pension funding pressures.”

That is not the legacy Christie had in mind, but it’s hard to see how he can avoid it. The governor has plausibly argued that the state needs even deeper pension reforms, such as a 401(k)-style plan for state workers — something that he didn’t propose at the peak of his first-term power and popularity and that there’s little chance the legislature will enact now.

There will be those inclined to see Christie’s latest crisis in the context of Bridgegate and to celebrate it as part of the brash and bullying governor’s comeuppance.

But putting one of the nation’s worst public pension systems back on a sustainable fiscal footing was and is a worthy cause. Christie’s pursuit of it represented what seemed so promising about him, politically and substantively.

The failure of reform, in a state that so desperately needs it, would be bad news for the entire country, whatever you might think of Christie or his presidential ambitions.